<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Common Functions : CodeIgniter User Guide</title>

<style type='text/css' media='all'>@import url('../userguide.css');</style>
<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />

<script type="text/javascript" src="../nav/nav.js"></script>
<script type="text/javascript" src="../nav/prototype.lite.js"></script>
<script type="text/javascript" src="../nav/moo.fx.js"></script>
<script type="text/javascript" src="../nav/user_guide_menu.js"></script>

<meta http-equiv='expires' content='-1' />
<meta http-equiv= 'pragma' content='no-cache' />
<meta name='robots' content='all' />
<meta name='author' content='ExpressionEngine Dev Team' />
<meta name='description' content='CodeIgniter User Guide' />

</head>
<body>

<!-- START NAVIGATION -->
<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
<div id="nav2"><a name="top"></a><a href="javascript:void(0);" onclick="myHeight.toggle();"><img src="../images/nav_toggle_darker.jpg" width="154" height="43" border="0" title="Toggle Table of Contents" alt="Toggle Table of Contents" /></a></div>
<div id="masthead">
<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
<tr>
<td><h1>CodeIgniter User Guide Version 2.1.3</h1></td>
<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
</tr>
</table>
</div>
<!-- END NAVIGATION -->


<!-- START BREADCRUMB -->
<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
<tr>
<td id="breadcrumb">
<a href="http://codeigniter.com/">CodeIgniter Home</a> &nbsp;&#8250;&nbsp;
<a href="../index.html">User Guide Home</a> &nbsp;&#8250;&nbsp;
Auto-loading Resources
</td>
<td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide&nbsp; <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" />&nbsp;<input type="submit" class="submit" name="sa" value="Go" /></form></td>
</tr>
</table>
<!-- END BREADCRUMB -->

<br clear="all" />


<!-- START CONTENT -->
<div id="content">

<h1>Common Functions</h1>

<p>CodeIgniter uses a few functions for its operation that are globally defined, and are available to you at any point. These do not require loading any libraries or helpers.</p>

<h2>is_php('<var>version_number</var>')</h2>

<p>is_php() determines of the PHP version being used is greater than the supplied <var>version_number</var>.</p>

<code>if (is_php('5.3.0'))<br />
{<br />
&nbsp;&nbsp;&nbsp;&nbsp;$str = quoted_printable_encode($str);<br />
}</code>

<p>Returns boolean <kbd>TRUE</kbd> if the installed version of PHP is equal to or greater than the supplied version number.  Returns  <kbd>FALSE</kbd> if the installed version of PHP is lower than the supplied version number.</p>


<h2>is_really_writable('<var>path/to/file</var>')</h2>

<p>is_writable() returns TRUE on Windows servers when you really can't write to the file as the OS reports to PHP as FALSE only if the read-only attribute is marked. This function determines if a file is actually writable by attempting to write to it first. Generally only recommended on platforms where this information may be unreliable.</p>

<code>if (is_really_writable('file.txt'))<br />
{<br />
&nbsp;&nbsp;&nbsp;&nbsp;echo &quot;I could write to this if I wanted to&quot;;<br />
}<br />
else<br />
{<br />
&nbsp;&nbsp;&nbsp;&nbsp;echo &quot;File is not writable&quot;;<br />
}</code>

<h2>config_item('<var>item_key</var>')</h2>
<p>The <a href="../libraries/config.html">Config library</a> is the preferred way of accessing configuration information, however config_item() can be used to retrieve single keys. See Config library documentation for more information.</p>

<h2>show_error('<var>message</var>'), show_404('<var>page</var>'), log_message('<var>level</var>', '<samp>message</samp>')</h2>
<p>These are each outlined on the <a href="errors.html">Error Handling</a> page.</p>

<h2>set_status_header(<var>code</var>, '<var>text</var>');</h2>

<p>Permits you to manually set a server status header.  Example:</p>

<code>set_status_header(401);<br />
// Sets the header as:  Unauthorized</code>

<p><a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html">See here</a> for a full list of headers.</p>


<h2>remove_invisible_characters(<var>$str</var>)</h2>
<p>This function prevents inserting null characters between ascii characters, like Java\0script.</p>


<h2>html_escape(<var>$mixed</var>)</h2>
<p>This function provides short cut for htmlspecialchars() function. It accepts string and array. To prevent Cross Site Scripting (XSS), it is very useful.</p>

</div>


<!-- END CONTENT -->


<div id="footer">
<p>
Previous Topic:&nbsp;&nbsp;<a href="autoloader.html">Auto-loading Resources</a><a href="hooks.html"></a>
&nbsp;&nbsp;&nbsp;&middot;&nbsp;&nbsp;
<a href="#top">Top of Page</a>&nbsp;&nbsp;&nbsp;&middot;&nbsp;&nbsp;
<a href="../index.html">User Guide Home</a>&nbsp;&nbsp;&nbsp;&middot;&nbsp;&nbsp;
Next Topic:&nbsp;&nbsp;<a href="routing.html">URI Routing</a></p>
<p><a href="http://codeigniter.com">CodeIgniter</a> &nbsp;&middot;&nbsp; Copyright &#169; 2006 - 2012 &nbsp;&middot;&nbsp; <a href="http://ellislab.com/">EllisLab, Inc.</a></p>
</div>

</body>
</html>